The present invention relates to an IC socket module for attaching an IC to an IC socket so as to connect terminals of the IC socket with the external wiring via leads, in order to carry out the electric property evaluation of the internal wiring of the IC at a high temperature.
As illustrated in FIG. 10, the internal wiring and wiring members of an IC (Integrated Circuit) 100 has conventionally been evaluated by carrying out voltage source current measurement or current source voltage measurement with respect to the IC 100 packaged in an IC socket 101.
In these measurement, a heat test is carried out in addition to the check of the initial condition at normal temperatures. In the heat test, the IC 100 is measured at a high temperature, in order to accelerate the degradation of the electric property thereof.
The conventional test at a high temperature is carried out inside a high-temperature thermostatic oven, as illustrated in FIGS. 11 through 13. To figure out the life and electric property of each IC 100 using a statistical method, the number of sample ICs is usually around 10-20.
When carrying out the test, as FIG. 11 shows, a plurality of ICs 100 connected with the corresponding IC sockets 101 are provided on openings (not illustrated) of respective stainless plates 102. Then, as also illustrated in FIG. 12, each of the IC sockets 101 is connected with an extension substrate 104, provided on a surface in a lengthwise direction of the stainless plate 102; the surface and the stainless plate 102 are arranged so as to form a common surface, via a coaxial cable 103 provided on the reverse side of the respective stainless plates 102. The extension substrates 104 protrude from a thermostatic oven 105. Therefore, by connecting a card edge connector 106 with the edge of the respective extension substrates 104, it is possible to acquire signals from the internal wiring and wiring members of the respective ICs 100 using an external measuring circuit (not illustrated), via wires connected to the respective card edge connectors 106.
The aforementioned sample ICs are, as illustrated in FIGS. 11 and 12, provided side by side in the thermostatic oven 105, without touching each other. As shown in FIG. 13, the sample ICs are exposed to a high temperature using a heater 107 of the thermostatic oven 105, and at this moment, a blower 109 driven by a blower motor 108 circulates air inside the thermostatic oven 105.
Incidentally, in this test, the lives (electric property) of the samples considerably vary in accordance with the Arrhenius equation when the temperature of the samples changes, so that it is important to keep the temperature of the samples consistent.
In this regard, in the conventional method, the temperature of the thermostatic oven 105 tends to be different between sample ICs provided in different parts of the thermostatic oven 105, so that the test data is considerably erratic. Thus it has been difficult to acquire accurate test results.
So, to keep the temperature of the sample ICs consistent, for instance, there is a sample heating method disclosed by Japanese Laid-Open Patent Application No. 8-220187/1996 (Tokukaihei 8-220187; published on Aug. 30, 1996).
As illustrated in FIG. 14, this sample heating method is arranged such that samples 203 are provided on a heating block 202 in a testing room 201 which is covered with a heat insulating material, and the samples 203 are directly heated at a high temperature. In this procedure, pins 204 of the respective samples 203 are inserted into pin holes 206 of a sample attaching substrate 205, and the sample attaching substrate 205 is screwed on the heating block 202 by a screw 207, etc. On this account, the electric property of the samples 203 can be accurately measured without the difference of the temperatures, according to this invention.
However, in the conventional evaluation system using the heating block, since a large amount of heat is dissipated from the sample attaching substrate 205 (i.e. from the IC sockets 101) via the samples 203, the variation of heat resistance due to this heat dissipation greatly degrades the temperature distribution of the samples.
One of the reasons of this degradation of the temperature distribution is the increase of an evaluation temperature. The evaluation temperature of 350xc2x0 C. is now required for the currently-used copper wiring in the IC 100 in the state of electro-migration, while in the past the evaluation temperature for aluminum wiring was 250xc2x0 C. at the maximum.
Moreover, owing to the miniaturization of wiring in the semiconductor device, the measuring current is getting smaller so that units of fA (femtoampere=10xe2x88x9215A) have currently been used for the measurement. To measure such a minute current, it is necessary to reduce the disturbance noise affecting the measuring system as much as possible. However, a high-insulating material conventionally used for the shielding arrangement for reducing the disturbance noise, such as Teflon (registered trademark), etc., is not usable at a high temperature of 350xc2x0 C.
The objective of the present invention is to provide an IC socket module in which the temperature of an IC is kept consistent when the evaluation of the internal wiring and wiring members of the IC is carried out at a high temperature.
To achieve the objective above, for carrying out electric property evaluation of internal wiring of the IC at a high temperature, the IC socket module in accordance with the present invention includes: an IC socket to which the IC is attached; protrusions, which are provided on the IC socket, for forming a gap between the IC socket and the IC; terminals which are attached to the IC socket; leads which are connected with the respective terminals; and coaxial connectors which are connected with (i) the respective leads and (ii) external wiring, the IC attached to the IC socket being directly in touch with a heating member so as to make the IC have a high temperature.
According to this invention, since the IC socket is provided with the protrusions for forming the gap between the IC socket and the IC, the IC is in touch with the IC socket only at the protrusions. Thus when the IC is heated by the heating member, the thermal conduction from the IC to the IC socket is small.
Consequently, it is possible to provide the IC socket module in which the temperature of the IC is kept consistent when the evaluation of the internal wiring and wiring members of the IC is carried out at a high temperature.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.